[3] Castelnuovo's other films include Rocco and His Brothers (1960), Camille 2000 (1969), L'emmerdeur (1973), Il prato macchiato di rosso (1973), Massacre Time (1966), The Five Man Army (1969), and The English Patient (1996).

In 1957, Castelnuovo debuted as a mime in the RAI children's television show Zurli il mago del giovedì.

[1] When the American television show Disneyland travelled to Italy in 1962, he appeared with Annette Funicello in two episodes of the mini-movie, Escapade in Florence, singing, playing the guitar, and adding the Italian verses to the jovial tarantella "Dream Boy".

[5] Castelnuovo's breakthrough role arrived with The Umbrellas of Cherbourg (1964), directed by Jacques Demy, in which he played opposite Catherine Deneuve.

[7] He appeared as Kenny Butler in the 2016 The Legacy Run with sport personalities Daniela Scalia, Luca Tramontin, Marco Baron, Flavien Conne, Ivan Asic, and Stefania Bianchini.